1. Field of the Invention
The present invention generally relates to an information storage apparatus such as a magnetic disk apparatus and an optical disk apparatus, and more particularly, to an information storage apparatus that can relocate data stored in posteriori defective sectors so as not to lose the data, without lowering data transfer speed, and a method of relocating the data.
An information storage apparatus is inspected before shipment from a factory. If any defective sector is found in the information storage medium of the information storage apparatus, the information storage apparatus is programmed not to write data in the defective sector. Data are automatically stored only in good sectors.
After the shipment from the factory, however, some good sectors may be damaged while in use. The information storage apparatus relocates data stored in the posteriori defective sectors to alternative sectors so as not to lose the data.
2. Description of the Related Art
The market for audio visual apparatuses that use disk-type information storage apparatuses such as hard disk drives and rewritable optical disk drives is expanding.
A hard disk drive, for example, is inspected when it is initialized in its manufacturing process. If any initial defective sector is found, the positional information of the initial defective sector is recorded in a particular area of the magnetic disk of the hard disk drive.
Logical block addresses (LBAs) are assigned from the top sector of the user data area, but the initial defective sectors are skipped based on the positional information. The hard disk drive writes and reads data using the logical block address as an identifier. In addition, since the hard disk drive needs a large enough number of sectors, backup sectors are additionally prepared on the magnetic disk.
It is possible to avoid using the initial defective sectors because the logical block addresses are assigned only to good sectors other than the initial defective sectors. The logical block addresses are assigned so that the seek time and rotational delay time of a magnetic head are minimized. The data transfer speed of the hard disk drive is consequently improved.
On the other hand, if any good sector is damaged after shipment, data stored in the damaged sector (posteriori defective sector) are relocated to a backup sector, and the backup sector is used on behalf of the posteriori defective sector. Accordingly, it is possible to prevent the posteriori defective sectors from being used and to improve the reliability of the hard disk drive.
By the way, even if some good sectors are damaged and backup sectors are accessed on their behalf, it is desired that the data transfer speed not be lowered. The assignment of the logical block addresses needs to be modified so that the data transfer speed is not lowered. If the data transfer speed is lowered, various problems may occur. For example, a motion picture that is played may stop momentarily.
The assignment of the logical block addresses is changed in the entire region in which user data are stored. New posteriori defective sectors may be found during the change. In addition, the user data may be lost due to power failure.